3.0's are great engines. I have one in my truck, and they have potential in them like any other truck. I'm averaging 15-16 mpg, with an automatic tranny in town, with stop and go traffic lights. Just to and from school, my engine is cold half way there, and I've got about seven lights to stop at. I get about 20.5 mpg on the highway. The way I see it, if you can afford to buy the truck, than you can afford to fill the fuel tank too. Plus, with a manual transmission, you will do a lot better than me on MPG. You could proably get 18-19 in the city.
If the truck looks clean, no stains, no scratches or dents, looks like something you would take care of, than the engine is probably the same way. If the person would drive his truck for 67000 miles and keep it clean, no stains, tears, no dents or scratches that havent been repaired, and the engine comaprtement is clean, then chances are he kept up on the engine. You can tell on the inside of the vehicle if they kept up on the engine. The 3.0 will last for ever.
The 3.0 isnt the most powerful engine, and if that is what your truly looking for, than your in for a dissapointment. Dont rev your engine at your buddies tacoma, thinking he has a pussy toyota. You wont beat him. I had that dissapointment.
I wouldnt pass the truck up because of its engine if thats what your looking for. If you NEED the power because your a landscape developer and you need the power to haul a bed full of soil up steep hills in San Francisco, than ok, otherwise there is always things you can do to get more out of your engine.